Thermal circuit closer



Feb. 12, 1929.

' J. M. JOHNSN THERMAL cmcuz'r cLossn Filed Jan. 20. 1927 nu .2.... Il..

gnmntoz Jam 1f. Jbfmson,

L m G Patented Feb. 12, 1929.

UNITED STATES JOHN M. JOHNSON, OF KANSAS CITY, MISSOURI.

THERMAL CIRCUIT CLOSER.

Application led January 20, 1927.

My invention relates to a thermal circuit closer including a fuse which is adapted to be destroyed at a predetermined temperature for the purpose of releasing a spring contact which closes an electric circuit including one or more suitable signals, and one object of' the invention is to provide a simple and inexpensive device of this character in which the fuse can be easily renewed after being burned l0 out.

A further object is to provide a device of this character which can be examined and repaired Without removing the device from any supporting means to which it may be applied.

While the device is capable of use in various situations, in the present instance I have shown it installed upon an internal combustion engine for the purpose of closing a signal circuit before said engine can become overheated to such an extent as to endanger its bearings.

In order that the invention may be fully understood, reference will now be had to the accompanying drawing, in which:

Fig. 1 shows the device applied to an engine.

Fig. 2 is a central vertical section of the device with the contacts thereof held in inactive position by fusible metal.

Fig. 3 is a view similar to Fig. 2, excepting that the fusible metal has been burned out and released the contacts, one of which has sprung into engagement with the internal portion of a housing forming a part of the device.

Fig. 4 is a detail of a spring member and a conductor for supporting said spring member.

Referring in det-ail to the different parts, 2 designates a tubular metallic housing having external threads 4 adjacent to one end and a circumferential shoulder 6 adjacent to said threads. The end of the housing 2, adjacent to the screw threads 4, is closed by a thin disk 7 of ,copper or other suitable metal, while the opposite end of the housing 2 is closed by a bushing 8 made of insulating material and threaded into said housing.

1() designates a binding post extending axially through the bushing 8 and into the housing 2. The binding post 10 is threaded into the bushing 8 and is further secured thereto by a lock-nut 12. The outer end of the binding post 10 is provided with a thumb nut 14 for securing one end of a Wire conductor 16 against the lock-nut 12 and said binding post 10.

18 designates a metallic conductor arranged serial No. 162,323.

within the housing 2 and threaded upon the inner end of the binding post 10.

20 designates a metallic spring member which. in the present instance, is folded midu'ay between its ends and fixedly mounted at its folded portion Within the conductor 18. The free. ends of the spring members 20 are bent in. opposite directions to form contacts 22, one or both of which are adapted to engage the. interior of the housing 2. Normally the contacts 22 are held together and out of engagement with the housing 2 by fusible solder 24.

In order to install the device on an engine it is only necessary to drill a small hole in the engine crank case or the oil pan and screw the threaded portion 4 of the housing 2 into said hole until the adjacent end of the shoulder 6 abuts the outer surface of said crank case or pan. After the housing 2 has been installed its inner end projects into and is exposed to the internal temperature of the engine and the composition of the fuse 24 is .such that it will become destroyed before such temperature arises to a high enough degree to endanger the crank shaft bearings.

As hereinbefore stated, the device may be used in various places and in connection with different kinds of circuits, but in the present instance I have shown it applied to the lower portion of an automobile engine A and arranged in a circuit consisting of the wire conductor 16, a battery B, a suitable visual signal such as a lamp 26 and a suitable audible signal such as a horn 28. Vith the engine A thus equipped it is apparent that should its temperature rise above normal while in operation and before its crank shaft bearings become damaged from overheating, the fuse 24 will become destroyed thereby releasing the spring member 2O so that its freed ends will spring apart and carry one or both of the contacts 22 into engagement with the interior of the housing 2, thus clos ing the circuit through the wire conductor 16, the battery B, the signal light 26, the horn 28, through ground to the engine A, the housing 2, the contact 22 and spring member 20, the conductor 18, the binding post 10 and back to the battery through the wire conductor 16, thereby notifying the driver of the car so that steps may be taken to correct the trouble which caused overheating of the engine. The disk 7 serves to prevent oil from splashing into the housing 2 and also prevents the melted fuse from running out into the engine.

After the fuse S24 has been destroyed as above stated, it is not necessary to remove the tubular housing- 2 from the engine in order to renew the fuse as such renewal may be accennglished by merely removing the bushing 8, after which the conductor 18 can be unscrewed `trom the binding post 10 and another conductor substituted with a spring member 2O having its contacts held together by a fuse, it beir j understood that a. supply oi' the conductors 18 With the springs 2() and fuses 2e may be carried under the seat of the motor vehicle ready for emergencies. rillhe ends of the spring members 20 from which the fuses have been destroyed can again bey secured together' at any convenient time With other fusible solder so that the conductors l and the spring members 2O circuity closer embodying the advantages above pointed out, and while I have shown and described the preferred construction and arrangement ot the several parts I reserve all rights to such changes and modications thereof as properly tall Within the spiritand scope oit the invention as claimed.

Having thus described my invention, what llf claim and desire to secure by Letters Patent, is:

A thermostatic circuit closer consisting of a tubular conductor housing threaded at one end in order that it may be screwed into an engine, metallic means for closing said threaded end, a bushing closing` the opposite end et said housing, a binding post extending into said housing through said bushing, a metallic conductor removably mounted upon the inner end of said binding post, a spring member oldedat its intermediate portion and secured to said metallic rconductor and having its ends` bent in opposite. directions to engage the innei-.surf'ace ofthehousing, and i'usible means for normally holding the ends of said spring member together and out of Contact With the housing.

in testimony whereof I atHX my signature.

JOHN M. JoI-iNsoN. 

